In material processing equipment such as mixers or mixing systems, it is common that a rotatable shaft assembly is supported by spherical and/or tapered bearing assemblies. This support is commonly accomplished by placing the bearing assemblies at various axial locations along the rotatable shaft. In particular, a mixing system may include an output impeller drive shaft that extends into a mixing vessel to drive an impeller and a hollow shaft that may encircle a portion of the output shaft. The hollow shaft may be rotationally coupled to the output shaft, and have a gear that is driven to transmit rotational motion to the hollow shaft. A first bearing or bearing set may be employed to support the output shaft, while a second bearing or bearing set may be utilized to support the hollow shaft.
The output shaft may be subject to high load and bending forces due to various mixing conditions during operation of a mixing system. These conditions may include, for example, shaft speed, physical properties of materials to be mixed, and shaft length. These forces may translate into bending forces that may cause the output shaft to deflect radially. The first and second bearings or bearing sets may isolate the hollow shaft from the output shaft and the associated bending loads the output shaft experiences. This may prevent the likelihood of the hollow shaft from transmitting undesirable loads to other components of the mixing system.
However, the second bearing or bearing set may be separated radially and/or axially from the gear by a portion of, or a separate component attached to a portion of, the hollow shaft which is surrounded by the second bearing or bearing set. As such, the rotation of the gear which is transferred to the hollow shaft and thereby the output shaft, is not directly supported by either of the first or second bearings or bearing sets. In addition, each of the first and second bearings or bearing sets may require a respective type of lubricant, for example oil for one bearing and grease for another bearing, to operate. This may require multiple lubricant sources and delivery mechanisms.
The mixing system may also include a frame assembly and bearing housings (e.g. bearing caps) mounted on the frame assembly which house each of the first and second bearings or bearing sets. The bearing housings include multiple components and may be mounted in such a way that bearing bores of respective bearings are not accurately aligned with one another. This can result in misalignment between the output shaft and the hollow shaft.
In view of the foregoing, there is a need for an arrangement of bearings which permits for multiple bearings to be lubricated by the same lubricant. In addition, there is a need for an apparatus and a method that improves bearing accuracy and performance while reducing a total number of parts required to transmit motion of a gear to a driven shaft.
These and other needs are addressed by the present disclosure.